[clang] [Sema] Return RecoveryExpr for ARC atomic ownership error (PR #224849)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: ʟᴜɴᴇx (im-lunex)

<details>
<summary>Changes</summary>

`BuiltinAtomicOverloaded` returned a bare `ExprError()` on the ARC
ownership check and made CodeGen hit `llvm_unreachable`.
so return a `RecoveryExpr` instead so bad data can't reach codegen.

Fixes #<!-- -->222528.

---
Full diff: https://github.com/llvm/llvm-project/pull/224849.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaChecking.cpp (+4-1) 
- (added) clang/test/CodeGenObjCXX/objc-atomic-ownership-recovery.mm (+12) 


``````````diff
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index dcf91e901f57e..7e96895d4f91b 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -5739,7 +5739,10 @@ ExprResult Sema::BuiltinAtomicOverloaded(ExprResult TheCallResult) {
   case Qualifiers::OCL_Autoreleasing:
     Diag(DRE->getBeginLoc(), diag::err_arc_atomic_ownership)
         << ValType << FirstArg->getSourceRange();
-    return ExprError();
+
+    return CreateRecoveryExpr(TheCall->getBeginLoc(), TheCall->getEndLoc(),
+                              llvm::to_vector(TheCall->arguments()),
+                              TheCall->getType());
   }
 
   // Strip any qualifiers off ValType.
diff --git a/clang/test/CodeGenObjCXX/objc-atomic-ownership-recovery.mm b/clang/test/CodeGenObjCXX/objc-atomic-ownership-recovery.mm
new file mode 100644
index 0000000000000..f8583fe34682f
--- /dev/null
+++ b/clang/test/CodeGenObjCXX/objc-atomic-ownership-recovery.mm
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fobjc-runtime=macosx-10.14 -fobjc-arc -emit-llvm -o /dev/null %s -verify
+
+// Test for - https://github.com/llvm/llvm-project/issues/222528
+
+ at class incompatible;
+
+static incompatible *g;
+
+void integer(incompatible *o) {
+  __sync_bool_compare_and_swap(&g, 0, o); // expected-error {{cannot perform atomic operation on a pointer to type 'incompatible *__strong': type has non-trivial ownership}} \
+                                          // expected-error {{cannot compile this scalar expression yet}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/224849